1. Field of the Invention
This invention relates to a radiation image recording, read-out and reproducing apparatus for recording a radiation image, reading out the radiation image to obtain electric image signals, and reproducing the radiation image into a visible image on the basis of the image signals. This invention particularly relates to a radiation image recording, read-out and reproducing apparatus wherein a radiation image is recorded on a stimulable phosphor sheet capable of storing the radiation energy.
2. Description of the Prior Art
When certain kinds of phosphors are exposed to a radiation such as X-rays, .alpha.-rays, .beta.-rays, .gamma.-rays, cathode rays or ultraviolet rays, they store a part of the energy of the radiation. Then, when the phosphor which has been exposed to the radiation is exposed to stimulating rays such as visible light, light is emitted by the phosphor in proportion to the stored energy of the radiation. A phosphor exhibiting such properties is referred to as a stimulable phosphor.
As disclosed in U.S. Pat. Nos. 4,258,264, 4,276,473, 4,315,318 and 4,387,428 and Japanese Unexamined Patent Publication No. 56(1981)-11395, it has been proposed to use a stimulable phosphor in a radiation image recording and reproducing system. Specifically, a sheet provided with a layer of the stimulable phosphor (hereinafter referred to as a stimulable phosphor sheet) is first exposed to a radiation passing through an object such as the human body to have a radiation image of the object stored thereon, and is then scanned with stimulating rays which cause it to emit light in proportion to the stored radiation energy. The light emitted by the stimulable phosphor sheet upon stimulation thereof is photoelectrically detected and converted to electric image signals, which are processed as desired to reproduce a visible image having an improved image quality, particularly a high diagnostic efficiency and accuracy. The finally obtained visible image may be reproduced in the form of a hard copy or may be displayed on a cathode ray tube (CRT). In this radiation image recording and reproducing system, the stimulable phosphor sheet is used to temporarily store the radiation image in order to reproduce the final visible image therefrom on a final recording medium. For economical reasons, therefore, it is desirable that the stimulable phosphor sheet be used repeatedly.
In order to reuse stimulable phosphor sheets as mentioned above, the radiation energy remaining on the stimulable phosphor sheet after it is scanned with stimulating rays to read out the radiation image stored thereon should be erased by exposing the stimulable phosphor sheet to light or heat as described in, for example, U.S. Pat. No. 4,400,699 or Japanese Unexamined Patent Publication No. 56(1981)-12599 corresponding to U.S. Ser. No. 168,806 (abandoned). The stimulable phosphor sheet should then be used again for radiation image recording.
From the aforesaid viewpoint, the applicant proposed in Japanese Unexamined Patent Publication No. 59(1984)-192240 corresponding to U.S. Ser. No. 037,119, a radiation image recording and read-out apparatus comprising:
i) a circulation and conveyance means for conveying at least one stimulable phosphor sheet for recording a radiation image thereon along a predetermined circulation path,
ii) an image recording section disposed on the circulation path for recording a radiation image of an object on the stimulable phosphor sheet by exposing the stimulable phosphor sheet to a radiation passing through the object,
iii) an image read-out section disposed on the circulation path and provided with a stimulating ray source for emitting stimulating rays for scanning the stimulable phosphor sheet carrying the radiation image stored thereon at the image recording section, and a photoelectric read-out means for detecting light emitted by the stimulable phosphor sheet scanned with the stimulating rays to obtain electric image signals, and
iv) an erasing section disposed on the circulation path for, prior to the next image recording on the stimulable phosphor sheet for which the image read-out has been carried out at the image read-out section, having the stimulable phosphor sheet release the radiation energy remaining on the stimulable phosphor sheet,
whereby the stimulable phosphor sheet is circulated through the image recording section, the image read-out section and the erasing section, and reused for radiation image recording. With the radiation image recording and read-out apparatus having such a configuration, the radiation image recording and read-out can be carried out sequentially and efficiently.
However, with the radiation image recording and read-out apparatus having the aforesaid configuration wherein a plurality of the stimulable phosphor sheets are circulated and conveyed along the circulation path and sequentially sent to the image recording section, the image read-out section and the erasing section, the apparatus becomes large. Also, in order to reproduce the radiation image detected by the aforesaid apparatus into a visible image, an independent image reproducing apparatus is necessary. Therefore, at the time the reproduced visible radiation image is to be used for viewing purposes, particularly for diagnostic purposes, it is necessary for the operator to proceed to the location of the image reproducing apparatus or to have the reproduced visible radiation image sent from the location of the image reproducing apparatus.
Accordingly, with the aforesaid conventional radiation image recording and read-out apparatus, it is not always possible to satisfy the need in the medical field or the like for recording a radiation image at a desired location and viewing the reproduced visible radiation image at the location immediately after the image recording is carried out.